Systems and methods for a wireless network connection point locator

ABSTRACT

Systems and methods for determining the presence of a wireless network connection point based upon wireless network characteristics. Examples of such characteristics include, but are not limited to: message length, repetition rate and response timing. These types of characteristics are used to differentiate various types of wireless networks from other radio frequency signals within a given band. The output of the locator is compared against desired thresholds to indicate signal strengths roughly corresponding to current wireless networks cards.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a non-provisional application and claims the benefitof Application No. 60/478,006, filed Jun. 11, 2003, entitled “Method andApparatus for Portable Wireless Network Location System,” (AttorneyDocket No. 14572P-069700US), the disclosure of which is incorporatedherein by reference for all purposes.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSOREDRESEARCH AND DEVELOPMENT

NOT APPLICABLE

REFERENCE TO A “SEQUENCE LISTING,” A TABLE, OR A COMPUTER PROGRAMLISTING APPENDIX SUBMITTED ON A COMPACT DISK.

NOT APPLICABLE

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to systems and methods for locating awireless network connection point and, more particularly, to systems andmethods for detecting the presence of a wireless network.

2. Description of the Prior Art

Portable computers, laptop computers, notebook computers, personaldigital assistants (PDAs), and other portable electronic devices areextremely popular in today's modern society. It is extremely importantfor many people, both professionally and personally, to be able toretrieve, in real time, various types of information. It is oftenespecially important to such people to retrieve various types ofmessages.

Accordingly, many of these people rely on their portable electronicdevices for accessing networks so that they may retrieve information andmessages conveniently. Unfortunately, it is currently a time consumingtask to power up and log on to a portable computer or electronic deviceonly to find that a wireless network connection point is not available,thus wasting the person's time and wasting power.

SUMMARY OF THE INVENTION

Broadly, the present invention provides systems and methods fordetermining the useable presence of a wireless network connection pointbased upon various message envelope characteristics. Examples of suchcharacteristics include message length, repetition rate and responsetiming. These types of characteristics are used to differentiate varioustypes of network connections from other signals within a given radiofrequency band. The output of a locator in accordance with the presentinvention indicates signal strength.

Thus, in accordance with the present invention, a portable device fordetermining the useable presence of a wireless network connection pointincludes a radio frequency detector that has a signal processor forevaluating a detected signal based upon wireless networkcharacteristics. The device further includes an indicator that indicatesat least the presence of a detected signal.

In accordance with one aspect of the present invention, the devicefurther includes a signal strength indicator.

In accordance with another aspect of the present invention, theindicator indicates that the device is searching for useable presence ofa wireless network connection point.

Also in accordance with the present invention, a method of determiningthe useable presence of a wireless network connection point includessearching for a signal. Upon detecting a signal, the detected signal isevaluated based upon wireless network characteristics. Based on thesecharacteristics, the signal is identified as IEEE 802.11b, IEEE 802.11g,Bluetooth, GSM cellular telephone, PCS cellular telephone, cordlessland-line telephone, or various other Radio Frequency standards. Thepresence and/or type of the detected signal is indicated.

In accordance with one aspect of the present invention, a floatingthreshold may be used to discern the signal from ambient RF noise. Bydetecting the strength of coherent signals with respect to ambient RFnoise, the threshold of detection is equivalent to that of a WNIC PCCard. One example includes coherent signals being detected that are lessthan 3 deciBels (dB) above the ambient RF noise.

In accordance with another aspect of the present invention, the methodalso includes indicating the strength of the detected signal. By use ofa logarithmic detector, the signal strength range is equivalent to thesignal strength readings of typical WNIC PC Cards, and the signalstrength indication is calibrated to the signal strength readings oftypical WNIC PC Cards.

In accordance with a further aspect of the present invention, the methodalso includes indicating that no signal is detected if no relevant orcoherent signal is detected above the ambient RF noise level.

In accordance with yet another aspect of the present invention, thedevice is fully portable and self-contained.

In accordance with a further aspect of the present invention, the deviceoptimizes energy use so that it may operate in excess of one year inordinary use.

In accordance with yet another aspect of the present invention, thedirection of the wireless network Access Point may be determined byincorporation of a directional antenna or by comparing the timing and/orstrength of signals from at least two antennae.

In accordance with a further aspect of the present invention, directionof the wireless network Access Point may be indicated by additionalindicator(s).

Other features and advantages of the present invention will be apparentin view of the following detailed description of preferred exemplaryembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an example of a network locator inaccordance with the present invention; and

FIG. 2 is a block diagram for an example of a pulse detector for usewith a network locator in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a wireless network connection pointlocator that is a hand-held indicator of the usable presence of awireless network connection point. The device allows a user to recognizethat a connection point is available before embarking on the timeconsuming and power-wasting task of powering up and logging on to aportable computer or other type of portable electronic device that iscapable of communicating with a wireless network. A signal strengthindicator is preferably included with the locator and allows the user toselect an optimal location for the wireless network connection and aseparate indicator preferably identifies that the device is scanning andno connection point is available.

FIG. 1 provides a perspective view of an example of a network locator100 in accordance with the present invention. The locator includes abody 101. On a surface of the body, a control button 102 is provided. Atleast one indicator 103 is provided. The indicator may be visual,audible, or tactile. In a preferred embodiment, there are threeindicators 103, 104 and 105. The indicators may be used, for example, toindicate levels of signal reception, power on/off and lack of a signal(or lack of a signal that meets a certain threshold). At least oneantenna 106 is also provided.

Broadly, a self-contained power source is provided that is small andlightweight for maximum portability, preferably, but not limited to“button cell” size (i.e. smaller than AAA). Nonetheless, power-savingfeatures allow the device to operate without replacing, recharging, orrefreshing the power source for at least one year in normal use (seeAppendix). Techniques to minimize power consumption include strobedsampling, automatic turn-off after 2 minutes, and the “on” switchprotected from accidental triggering.

Since the 2.4 GHz radio band is open and unregulated, a great manywireless technologies are present, including, for example, 802.11b,Bluetooth, microwave ovens, and cordless telephones. The design inaccordance with the present invention uses various messagecharacteristics, including, for example, message-length, repetitionrate, number of repetitions, response timing, and frequency distributionto differentiate various types of network connections from all othersignals in the band. For example, an 802.11b base station may bedistinguished by a beacon pulse of between 200 and 1200 uSec.transmitted between 5 and 20 times per second. Bluetooth networks may beidentified by envelope pulse (120 uSec) width as well as the correctrepetition rate (1025 uSec) and a unique frequency spectrum due to thechannel-hopping behavior.

A Wireless Network Interface Card (WNIC) is a frequency tuneable, directsequence spread spectrum receiver. A device in accordance with thepresent invention preferably uses a wideband front end to allow all theenergy in the band to drive the detector. Although this may cause somesignal overload and interference issues, in this case it also makes thedetector frequency insensitive, i.e. no frequency tuning required, andeliminates the need to de-spread the signal.

A variable comparison point, or floating threshold is used todistinguish detected signals from the ambient RF noise levels. Signalsabove this threshold that match the wireless network envelopecharacteristics are preferably identified on a signal strengthindicator. Using an adaptive scheme allows detection of the signal atfield strengths approaching the sensitivity levels of WNIC cards.

The RF detector preferably provides an analog output that correspondslinearly to the logarithmic strength of the input signal. This allows adynamic range comparable to WNIC cards, and the output of the detectoris used to indicate signal strength, which signal strength levelindication is calibrated to thresholds that are meaningful with respectto relevant mobile electronic devices.

A directional antenna or the timing of multiple readings, preferablyfrom at least two antennas, are analyzed to determine the direction ofthe wireless network Access Point. The direction is preferably indicatedby a separate visual, audible, or tactile indicator.

FIG. 2 provides a schematic for an example of electronics for locator100. An antenna 200 is provided that is communicatively coupled to aband filter 201, preferably an ISM band filter, to avoid saturation. Anamplifier 202 is communicatively coupled to band filter 201 and a secondband filter 203, which is also preferably an ISM band filter. A secondamplifier 204 is communicatively coupled to band filter 203 and log ampdetector 205. An operational amplifier arrangement 206 is coupled to thelog amp detector for providing pulse comparison, noise level samplingand signal signaling. The operational amplifier arrangement is coupledto microprocessor 207.

A plurality of power switches 208 are also provided. The power switchespreferably comprise PNP transistors that disable the amps and detectorcircuitry. A power source 209, preferably in the form of one or twolithium batteries, is provided. The battery(s) is preferably in the formof three volt coin cell batteries. Indicators 210 are provided forillustrating things such as activity of the device, detection of variousnetworks and possible lack of detection. Preferably these indicators arein the form of LEDs. Audible and/or tactile indicators may also be used,either alone or in conjunction with the LED indicators. An activationswitch 211 is preferably provided to activate locator 100. Preferably,locator 100 turns off automatically in order to conserve power after apredetermined amount of time. A Boundary Scan interface (JTAG-IEEE1149.1) 212 is also preferably provided. Finally, a crystal oscillator213 coupled to the microprocessor is also preferably included.

The antenna is preferably a printed dipole. The band filters arepreferably SAW-filters having an I.L. of 2.5 dB and are preferably 100MHz wide. The amplifiers are preferably 4 mA@3V and have a 14 dB gainand 2.5 dB NF. The log amp-detector preferably has 45 dB DR with −45 dBmsensitivity and 5 mA@2.7V with 30 mV/dB. The pulse comparativepreferably operates at 6 dB peaks above the noise sample.

The foregoing descriptions of specific embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The embodiments were chosen and described in order to bestexplain the principles of the invention and its practical application,to thereby enable others skilled in the art to best utilize theinvention and various embodiments with various modifications as aresuited to the particular use contemplated. It is intended that the scopeof the invention be defined by the claims appended hereto and theirequivalents.

1. A portable device for determining the presence of a wireless network,the device comprising: a radio frequency detector including a signalprocessor for evaluating a detected signal based upon wireless networkcharacteristics; and at least indicator that indicates at least thepresence of a detected signal.
 2. A portable device in accordance withclaim 1 wherein the network characteristic used for detection is thepresence of a repeated signal.
 2. A portable device in accordance withclaim 1 wherein the network characteristic used for detection is thepresence of a repeated beacon message used to indicate a wireless accesspoint
 3. A portable device in accordance with claim 1 wherein thenetwork characteristic used for detection is the length of a repeatedbeacon message used to indicate a wireless access point.
 5. A portabledevice in accordance with claim 1 wherein the network characteristicused for detection is the repetition rate of a repeated beacon messageused to indicate a wireless access point.
 6. A portable device inaccordance with claim 1 further comprising a signal strength indicator.7. A portable device in accordance with claim 1 wherein the indicatorindicates that the device is searching for the presence of a wirelessnetwork.
 8. A portable device in accordance with claim 1 wherein thesignal processor provides output that corresponds to the strength of thedetected signal.
 9. A portable device for determining the presence of awireless signal, the device comprising a radio frequency detector thatdetects the presence of a wireless signal if the signal is above athreshold.
 10. A portable device in accordance with claim 9 wherein afloating threshold above ambient noise is used to detect the presence ofa wireless signal.
 11. A portable device in accordance with claim 10wherein the floating threshold is a predetermined threshold.
 12. Aportable device in accordance with claim 11 wherein the predeterminedthreshold is approximately 3 dB above ambient noise.
 13. A portabledevice in accordance with claim 9 wherein a predetermined threshold isused to detect the presence of a wireless signal.
 14. A portable devicein accordance with claim 9 further comprising means for indicating thatno signal is detected if no signal is detected above a threshold.
 15. Aportable device in accordance with claim 9 further comprising means forindicating the strength of the detected signal.
 16. A portable device inaccordance with claim 15 wherein the signal strengths are determined bycomparing the signal strength against discrete thresholds.
 17. Aportable device in accordance with claim 16 wherein there are at leasttwo discrete thresholds.
 18. A portable device for determining theusable presence of a wireless network connection point, the devicecomprising: a radio frequency detector including a signal processor forevaluating a detected signal based upon wireless network envelopecharacteristics; and an indicator that indicates at least the presenceof a detected signal.
 19. A portable device in accordance with claim 18further comprising a signal strength indicator.
 20. A portable device inaccordance with claim 18 wherein the at least one indicator indicatesthat the device is searching for the useable presence of a wirelessnetwork connection point.
 21. A portable device in accordance with claim18 wherein the signal processor provides an analog output thatcorresponds linearly to the logarithmic strength of the detected signal.22. A portable device for determining the usable presence of a wirelessnetwork connection point, the device comprising: a radio frequencydetector including a processor for determining a detected signal basedupon wireless network envelope characteristics; an indicator thatindicates at least the presence of a detected signal and that the deviceis searching for the useable presence of a wireless network connectionpoint; and a signal strength indicator; wherein the processor providesan analog output that linearly approximates the logarithmic strength ofthe detected signal.
 23. A method of determining the usable presence ofa wireless network connection point, the method comprising: searchingfor a signal; upon detecting a signal, evaluating the detected signalbased upon wireless network envelope characteristics; and indicating thepresence of the detected signal if the detected signal is above apredetermined threshold.
 24. A method in accordance with claim 23wherein the floating threshold is predetermined, e.g. at approximately 3dB above ambient noise.
 25. A method in accordance with claim 23 furthercomprising indicating a strength of the detected signal.
 26. A method inaccordance with claim 23 further comprising indicating that no signal isdetected if no signal is detected above a predetermined threshold.
 27. Amethod in accordance with claim 25 wherein the signal strengths aredetermined by comparing the signal strength against discrete analogthresholds.
 28. A method in accordance with claim 27 wherein there areat least two thresholds.
 29. A method of determining the usable presenceof a wireless network connection point, the method comprising: searchingfor a signal; upon detecting a signal, evaluating the detected signalbased upon wireless network envelope characteristics; indicating thepresence of the detected signal if the detected signal is above apredetermined threshold; and indicating a strength of the detectedsignal.
 30. A method in accordance with claim 29 further comprisingindicating that no signal is detected if no signal is detected above apredetermined threshold.
 32. A method in accordance with claim 29wherein the signal strengths are determined by comparing the signalstrength against discrete analog thresholds.
 32. A method in accordancewith claim 31 wherein there are at least two thresholds.